The present invention relates to compressed fluid systems for vehicles. It finds particular application in conjunction with systems utilizing a pair of air dryers for removing moisture from compressed air and will be described with particular reference thereto. It will be appreciated, however, that the invention is also amenable to other like applications.
Transit coaches and air-assisted bulk-off load units are illustrative of compressed air systems used for operating brakes and accessories (e.g., tire inflation systems) of vehicles (e.g., heavy-duty trucks, tractors, trailers, or tractor-trailer combinations). Known air dryers cannot meet the demands of these systems. More specifically, a desiccant material in the air dryer becomes overwhelmed and saturated, ultimately resulting in loss of function.
Continuous flow air dryers are used for air brake vehicle applications where high air use calls for extended charging times and high compressor duty cycles. Continuous flow systems, therefore, typically use a pair of air dryers between a source of compressed air and a storage reservoir. By occasionally purging air to exhaust from an air dryer, the dryer (specifically, the desiccant material) is regenerated and is more effective in removing moisture during its next duty cycle. Accordingly, switching arrangements that alternate the pair of air dryers between charging the reservoir and purging (e.g., one air dryer is regenerated while the other air dryer supplies dry air to the reservoir) have been developed.
In current systems that alternate a pair of air dryers between charge and purge modes, the dried air from each of the dryers is transmitted to a common reservoir (e.g., a wet tank) before being distributed to a plurality of storage reservoirs. The wet tank includes pressure protection means for ensuring one of the reservoirs maintains a minimum threshold of pressure if another one of the tanks is depressurized due to, for example, a leak.
Additionally, the dryers are mounted to a module that controls the modes of the respective dryers. Such configurations require heavy and/or bulky bracketry for securing the dryers to the control module. The weight of the brackets may negatively affect vehicle performance. Furthermore, the size of the brackets consume a significant critical space along the vehicle frame.
The present invention provides a new and improved apparatus and method which address the above-referenced problems.
A continuous flow dryer system for compressed air includes a plurality of air dryers for alternately drying compressed air from a source. The dried air from a first of the dryers is transmitted to a second of the dryers before being distributed to a plurality of reservoirs via a plurality of respective control valves in the second air dryer.
In one embodiment of the invention, the continuous flow dryer system for compressed air includes first and second air dryers for alternately drying compressed air from a source. The dried air from the first dryer is transmitted to the second dryer. First and second reservoirs store the dried compressed air. A plurality of control valves in the second air dryer are used for distributing the dried air to the respective reservoirs.
In one aspect of the invention, the first and second dryers are mounted to the first and second reservoirs, respectively.
In another aspect of the invention, the control valves open for distributing the air as a function of a pressure in the second dryer relative to the pressures in the respective reservoirs.
In another aspect of the invention, the control valves are pressure on valves.
In another aspect of the invention, the control valves are electronically controlled valves.
In another aspect of the invention, the pressure in the second dryer required for opening the control valves becomes lower as the pressures in the respective reservoirs increase.
In another aspect of the invention, a pressure controller senses the pressure in the second dryer. If the pressure in the second dryer is below a pressure controller threshold, the pressure controller causes the source to deliver pressurized air to the dryers. If the pressure in the second dryer is one of equal and above the pressure controller threshold, the pressure controller causes the source to cease delivering pressurized air to the dryers.
In another aspect of the invention, a control module causes the dryers to alternate between a dry cycle and a regeneration cycle such that one of the dryers is in the dry cycle when the other dryer is in the regeneration cycle.
In another aspect of the invention, each of the reservoirs includes a purge chamber. A portion of the dried air is channeled to the purge chambers and is used during the regeneration cycles of the dryers.
In another aspect of the invention, a third reservoir receives and stores the dried compressed air from the second dryer. Each of the reservoirs is used in conjunction with a respective compressed air system.
In another embodiment of the present invention, a compressed air dryer system includes a first reservoir for storing compressed air, a first air dryer incorporated into the first reservoir, and a means for channeling the compressed dried air from the first dryer to the first reservoir. The compressed air is dried by the first dryer before being stored in the first reservoir.
In another embodiment of the present invention, a compressed air dryer system includes a first reservoir for storing compressed air and a first air dryer secured to the first reservoir. The compressed air is dried by the first dryer before being stored in the first reservoir. A first control valve controls a flow of the compressed dried air from the first dryer to the first reservoir.
In another embodiment of the present invention, a mechanism for compensating for a depressurization of a reservoir in a compressed air system includes a first reservoir for storing compressed air. A first air dryer is secured to the first reservoir. The compressed air is dried by the first dryer before being stored in the first reservoir. A first control valve opens for channeling the compressed dried air from the first dryer to the first reservoir as a function of respective pressures in the first dryer and the first reservoir.